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Message-ID: <YQy+9mSSzban+t/X@yekko>
Date: Fri, 6 Aug 2021 14:47:50 +1000
From: David Gibson <david@...son.dropbear.id.au>
To: Jason Gunthorpe <jgg@...dia.com>
Cc: "Tian, Kevin" <kevin.tian@...el.com>,
"Alex Williamson (alex.williamson@...hat.com)"
<alex.williamson@...hat.com>,
Jean-Philippe Brucker <jean-philippe@...aro.org>,
Jason Wang <jasowang@...hat.com>,
"parav@...lanox.com" <parav@...lanox.com>,
"Enrico Weigelt, metux IT consult" <lkml@...ux.net>,
Paolo Bonzini <pbonzini@...hat.com>,
Shenming Lu <lushenming@...wei.com>,
Joerg Roedel <joro@...tes.org>,
Eric Auger <eric.auger@...hat.com>,
Jonathan Corbet <corbet@....net>,
"Raj, Ashok" <ashok.raj@...el.com>,
"Liu, Yi L" <yi.l.liu@...el.com>, "Wu, Hao" <hao.wu@...el.com>,
"Jiang, Dave" <dave.jiang@...el.com>,
Jacob Pan <jacob.jun.pan@...ux.intel.com>,
Kirti Wankhede <kwankhede@...dia.com>,
Robin Murphy <robin.murphy@....com>,
"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
"iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
David Woodhouse <dwmw2@...radead.org>,
LKML <linux-kernel@...r.kernel.org>,
Lu Baolu <baolu.lu@...ux.intel.com>
Subject: Re: [RFC v2] /dev/iommu uAPI proposal
On Wed, Aug 04, 2021 at 11:04:47AM -0300, Jason Gunthorpe wrote:
> On Mon, Aug 02, 2021 at 02:49:44AM +0000, Tian, Kevin wrote:
>
> > Can you elaborate? IMO the user only cares about the label (device cookie
> > plus optional vPASID) which is generated by itself when doing the attaching
> > call, and expects this virtual label being used in various spots (invalidation,
> > page fault, etc.). How the system labels the traffic (the physical RID or RID+
> > PASID) should be completely invisible to userspace.
>
> I don't think that is true if the vIOMMU driver is also emulating
> PASID. Presumably the same is true for other PASID-like schemes.
Right. The idea for an SVA capable vIOMMU in my scheme is that the
hypervisor would set up an IOAS of address type "PASID+address" with
the mappings made by the guest according to its vIOMMU semantics.
Then SVA capable devices would be plugged into that IOAS by using
"PASID+address" type endpoints from those devices.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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